The present invention claims foreign priority under 35 U.S.C. § 119 based on Korean Patent Application No. 10-2003-0013531, filed Mar. 4, 2003, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates generally to a method of allocating an Internet Protocol (IP) address and detecting the duplication of the IP address in an ad-hoc network environment, and more particularly to a method of allocating an IP address and detecting the duplication of the IP address in an ad-hoc network environment, in which a terminal allocates an IP address to itself and efficiently detects and handles the duplication of the IP address in the ad-hoc network environment, thus reducing the load of an entire network and allowing the method to be used together with existing routing protocols.
2. Description of the Related Art
An ad-hoc network is a network that is established among wireless terminals in an environment with no infrastructure, in which there is no central server and, therefore, it is almost impossible to dynamically allocate an IP address to a wireless terminal using a Dynamic Host Configuration Protocol (DHCP) server or the like.
Accordingly, since an ad-hoc network has no central server, every terminal should have a zero configuration function of allocating its IP address to itself and allowing it to communicate with the other terminals.
When a terminal allocates an IP address to itself without a central server, it examines whether its IP address is unique throughout an ad-hoc network so as to prevent a collision of the IP address. The detection of a collision of an IP address in an ad-hoc network is considerably complicated, differently from that in a wired network. The reason for this is that since terminals move, there are complicated and unpredictable variations of network topology such as the merging of different networks with each other and the dividing of a network into a plurality of networks.
Up to now, there has been used the method, in which every terminal in an ad-hoc network has a unique Identification (ID), it is assumed that the unique ID is set to a Media Access Control (MAC) address or random number, and it is determined whether each pair of a unique ID and its corresponding IP address has a duplicate in the ad-hoc network.
In another method, it is assumed that every ad-hoc network has a unique ID for distinguishing one network from another. Such an ID may be set to a random number. The ID of the network allows the detection of the merging of two ad-hoc networks.
If it is assumed that every terminal has a unique ID, the terminal sends an IP address and a unique ID to the other terminals in the process of establishing a routing table. When the sent IP address is identical with an IP address in the routing table and the sent ID is different from that of a terminal having the same IP address in the routing table, it may be determined that two different terminals use the same IP address.
If it is assumed that every ad-hoc network has a unique ID, each terminal is allocated an IP address by existing terminals of the ad-hoc network. Accordingly, in this case, it may be appreciated that the duplication of the IP address does not occur. If two ad-hoc networks are merged with each other, the merging of the ad-hoc networks is detected through the IDs of the ad-hoc networks. Two ad-hoc networks can detect the duplication of the IP addresses of the ad-hoc networks by exchanging IP address allocation tables with each other. Duplicate IP addresses are re-allocated throughout all terminals of a merged ad-hoc network.
However, although the prior art technology assumes that unique IDs of a terminal and an ad-hoc network can be generated, it is almost impossible to generate unique IDs without a prior agreement or communications. In other words, since a MAC address may have a duplicate, it cannot be ensured that IDs are unique even though the IDs are generated based on MAC addresses. As a result, in the case where an ID has a duplicate, the prior art technology cannot detect the duplication of the IP address.
Additionally, in the conventional technology, since a broadcast is launched throughout an entire network, an excessive load is exposed on the network by the broadcast, thus overloading the network.
In brief, in the prior art technology, since the topology of an ad-hoc network is changed in an unpredictable manner, a complicated method should be used to detect the duplication of the IP address. Although various countermeasures are attempted to cope with various circumstances, the prior art technology is still weak to variations of network topology. Accordingly, the prior art technology is problematic in that it may be seriously affected by the movement of a terminal and a communications failure.